Bridlington Drift.—To this era belongs the well-known locality of Bridlington, near the mouth of the Humber, in Yorkshire, where about seventy species or well-marked varieties of shells have been found on the coast, near the sea-level, in a bed of sand several feet thick resting on glacial clay with much chalk débris, and covered by a deposit of purple clay with glaciated boulders. More than a third of the species in this drift are now inhabitants of arctic regions, none of them extending southward to the British seas; which is the more remarkable as Bridlington is situated in lat. 54° north. Fifteen species are British and Arctic, a very few belong to those species which range south of our British seas. Five species or well-marked varieties are not known living, namely, the variety of _Astarte borealis_ (called _A. Withami_); _ A. mutabilis_; the sinistral form of _Tritonium carinatum, Cardita analis,_ and _Tellina obliqua,_ Fig. 120, p. 194. Mr. Searles Wood also inclines to consider _Nucula Cobboldiæ,_ Fig. 119, p. 194, now absent from the European seas and the Atlantic, as specifically distinct from a closely-allied shell now living in the seas surrounding Vancouver’s Island, which some conchologists regard as a variety. _Tellina obliqua_ also approaches very near to a shell now living in Japan. Glacial Drift of Ireland.—Marine drift containing the last-mentioned Nucula and other glacial shells reaches a height of from 1000 to 1200 feet in the county of Wexford, south of Dublin. More than eighty species have already been obtained from this formation, of which two, _Conovulus pyramidalis_ and _ Nassa monensis,_ are not known as living; while _Turritella incrassata_ and _Cypræa lucida_ no longer inhabit the British seas, but occur in the Mediterranean. The great elevation of these shells, and the still greater height to which the surface of the rocks in the mountainous regions of Ireland have been smoothed and striated by ice-action, has led geologists to the opinion that that island, like the greater part of England and Scotland, after having been united with the continent of Europe, from whence it received the plants and animals now inhabiting it, was in great part submerged. The conversion of this and other parts of Great Britain into an archipelago was followed by a re-elevation of land and a second continental period. After all these changes the final separation of Ireland from Great Britain took place, and this event has been supposed to have preceded the opening of the straits of Dover.[1]